Method of constructing secondary members for induction-motors



l. H. MILLS.

METHOD OF CONSTRUCTING SECONDARY MEMBERS FOBlNDUCTION MOTOR& APPLICATION FlLEn nEcfla, 1917.

1,371,569. Patente Man 15 192i WlTNESSES WW M? AT'TORNEY UNITED STATES PATENT OFFTCE.

ISAAC H. MILLS, OF TURTLE GREEK, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

METHOD OF CONSTRUOTING SECONDARY MEMBERS FOR INDUCTION-MOTORS.

Application filed. December 13, 1917.

To aZZ whom itmag concern:

Be it known that 1, Isaac H. MiLLs, a citizen of the United States, and a resident of Turtle Creek, in the county of Allegheny and State of Pennsylvania, have invented a. new and useful Improvement in Methods of Constructing Secondary Members for Induction-Motors, of which the following is a specification.

My invention relates to the construction of secondary members for induction motors and particularly to the construction of windings for secondary members of the squirrel-cage type and to damping windings and amortisseur windings for dynamoelectrio machines.

@ne object of my invention is to provide a. process for manufacturing members of the above-indicated class which shall greatly reduce the cost ofsuch paits and improve their construction.

A further object of my invention is to provide a structure. that shall not require skilled workmen for assembling the same.

In the construction of windings of the types under discussion, it is customary prao tice to provide saw-cuts in the ends of the inductor bars and to secure the bars to the resistor, rings by expanding these cuts and bending the material at the sides thereof in opposite directions. This operation re quires a considerable degree of skill for its proper accomplishment, and the windings thus constructed are not uniform in appearance or in operation.

in accordance with my invention, 1 provide a rolling process which is applicable to either solid or split inductors for securing the inductor bars of squirrel-cage rotors to the resistance rings.

Figure 1 of the accompanying drawing is a view. in perspective, of a secondary member of an induction motor constructed in accordance with my invention; Fig. 2 is a side elevational view of a tool employed for expanding the ends of the inductor bars; Fig. 3 isa longitudinal sectional view of a portion of a secondary member partially completed; Fig. 4 is an end view of a portion of the member, shown in Fig. 3;

Fig. 5 is aview, partially in side elevation and partially in section, of apparatus for use in practising a modified process; Fig. 6 is a similar view illustrating a later step in the process; and Fig. 7 is an end view of Specification of Letters Patent.

Patented Mar. 155. 1921.

Serial No. 206,868.

a portion of a rotor resulting from the process indicated in Fig. 5.

The squirrel-cage secondary member of the induction motor that is illustrated in the drawing comprises two conducting, but preferably non-magnetizable, end plates 1 and intermediate magnetizable core punchings or laminae 2 which are provided with slots adjacent to their peripheries for the reception of inductor bars 3. The ends of the inductor bars 3 extend somewhat beyond the end plates 1, when initially assembled. but are subsequently mashed down by a fluted roller 4 which is applied, under pressure, to the ends of the bars 3 in order to expand the same and to securely clamp the core punchings 2 between the end plates 1.

When the inductor bars are initially positioned in the core slots. their ends project short distances beyond the end plates 1. as illustrated by the bars 5 of Fig. 1. The secondary member. thus assembled, is placed upon a cylindrical support 6 (Fig. 3) and the roller 4 is rolled over the ends of the bars, under considerable pressure, to expand the same. as shown at 7 (Fig. 1). The member is then inverted and the same process applied to the other ends of the bars.

The roller 4-, by means of which the expanding process is accomplished, together with its associated support, is shown in Fig. 2 of the drawing. A tapered shank 3 is adapted to be received in the chuck of a drill press, or other apparatus for its rotation, and is provided with a cross-head 9 upon which the roller arm 10 is adjustably mounted. A fluted roller 4, which has a central fin 11 for splitting the ends of the bars 3 and spreader portions 12, is rotatably mounted on the arm 10 and is adapted to be revolved by the rotation of the shank 8.

When pressure is applied to the roller 4 and it is rolled over the ends of the bars 3, the fin 11 serves to split the ends of the bars, and the spreader portions 12 draw the split portions of the bars laterally, in opposite directions, to form the expanded ends. This process requires very little time and may be performed by unskilled labor. The secondary members so constructed are uniform in structure and neat in appearance. and the electrical characteristics of the motors vary to a much less degree than in structures heretofore employed. A further advantage of this method of securing the bars to the end rings lies in the fact that cylindrical bars. as well as bars of square or oblong cross section, may be employed. After the rolling process has been completed, the electrical conductivity of the joint may be improved by dipping the end ring in molten solder or by brazing.

Figs. 5, 6 and 7 illustrate a modified form of my invention in which a split inductor 14 is composed of two separate portions placed in the armature slots from opposite ends. Each portion has one end bent to constitute a shoulder 15 and the other end is bent over by the tool 16 and the roller 17 after the bars are assembled in place. One

arm 90f a tool, such as that shown in Fig. 2, may be provided with a tool 16 which is pivotally mounted at 17 and is held in position by a stop 18 that is provided in the arm 10. After the ends of all of the bars at one end of the rotor are partially bent over by the application of the tool 16, the stop 18 is drawn out and a roller 17 is applied, under considerable pressure, to the ends of the bars 14. When'the stop 18 is withdrawn, the tool 16- may turn about the pivot 17 and thus become ineffective. The flat-faced roller 17,

' which may be carried on another arm of the tool shown in Fig. 2 is now applied, under pressure, to the partially bent tips of the inductor bars 14 in order to bend the same into close engagement with the end rings.

Although I have described my invention as applied to the construction of secondary members of induction motors, it is obviously not so limited but may be used for enlarging the heads of any series of elongated members or for expanding the protruding ends of rivets. I desire, therefore, that only such limitations shall be imposed as are set forth in theappended claims.

I claim as my invention:

1. The method of expanding the ends of a. plurality of elongated members which consists in assembling the members in side-byside relation and splitting and expanding the ends of said members by applying rolling pressure to the said ends successively.

2. The method of anchoring a plurality of elongated members which consists in assembling said members in spaced side-byside relation and splitting and mashing down the ends of said members in succession.

3. The method of assembling a plurality of elongated members arranged in side-byside relation around the periphery of a cylinder, which consists in moving a fluted roller over the ends of said members and exerting pressure thereon to split the ends of said members and bend the split portions away from one another.

The method of constructing a squirrelcage motor rotor which consists in placing solid inductor bars in slots in the periphery of a magnetizable core and moving a roller over the ends of said bars, under pressure, to substantially simultaneously split and expand the ends of said bars.

5. The method of constructing a squirrelcage rotor which consists in assembling a plurality of inductor bars between end rings and securing said bars to said end rings by simultaneously applyingsplitting and rolling pressure to the ends of said bars in succession.

6. The method of constructing a winding for dynamo-electric machines which consists in assembling a plurality of elongated conducting bars between resistor plates, through which they project, and applying rolling and splitting pressure to the ends of said bars in succession to expand the same.

7. The method of anchoring an elongated member within a structure which consists in positioning said member so as to have a protruding end portion and splitting and mashing down said protruding portion.

8. The method of assembling a. plurality of elongated members arranged in side-byside relation around the periphery of a cylinder, which consists in moving aroller over the ends of said members and simultaneously splitting and exerting pressure thereon to bend portions thereof away from one another.

9. The method of assembling a plurality of elongated members arranged in spaced parallel relation around the periphery of a cylinder, which consists in splitting the ends of said members by rolling pressure.

In testimony whereof I have hereunto subscribed my name this 30th day of N ov., 1917.

ISAAC H. MILLS. 

